Low Oil Pressure advice please

O

old camper

0
Hi everyone,

Smurf's oil light comes on in top at 30mph. I have cleaned out the pressure relief valve and this made no difference. I have just fitted an oil pressure gauge and the pressure does seem low, when hot, about35-'40 PSI max at 55mph in top and about 10-15 at 30 MPH and perhaps 5- 7psi on tickover. The engine has done 54000 miles, so I suspect crankshaft bearing wear. It runs sweetly, no rumbles or knocks even when starting -so sign of the 'death rattle' from a cold start.
There iss lots I could do, ranging from nothing till it makes nasty noises to a full engine rebuild with options like putting an engine oil treatment inor replacing just the big end shells. I only do 1500 or so miles each year and it dosent burn much oil. Advice appreciated, anyone solved or lived with similar problems, any idea how long it might go on for? Taking the engine out looks tricky!
Thanks
Martin
 
Normal oil pressure is 30/50 psi so it seems OK at the higher speeds but does seem a little low further down the rev range, the manual does say that tickover pressure is not important and the condition of the engine should be judged on normal running pressure. First thing to check is what oil are you using? it should be 20/50 as modern multigrades are a bit thin. You could be very unlucky and have a dodgy oil pressure switch and a gauge that is inaccurate (wishful thinking maybe) but it might be worth a try fitting a new switch to see what happens.
If all else fails it is possible to drop the sump with the engine still in the van, not a pleasant job laying on your back but maybe better than pulling the engine
 
New oil pressure relief valve is the cheapest and quickest thing to try. Could also be a worn oil pump which can be changed with the engine in.
 
Thanks for these suggestions, yes I am ussing 20/50 Multigrade. I shall try a differnt oil pressure switch next. Then a new relief valve
Martin- are the oil pumps prone to wear out? I could change this along with big end shells
 
Am I right in thinking a 1725 Hillman Hunter engine can be made to fit by changing sump, front engine plate etc?
Would this one do?
www.ebay.co.uk

HILLMAN HUNTER 1725CC COMPLETE ENGINE (71981369) | eBay

THIS IS A GENUINE HILLMAN HUNTER 1725 BLOCK WITH THE CASTING NUMBERS MATCHING THE ENGINE IS IN GOO RUNNING ORDER WOULD BE READY TO DROP IN THE CAR COULD DO WITH A BETTER CLEAN AND A GOOD SERVICE LOW MILEAGE CAR.
www.ebay.co.uk
Thanks
 
Yep, front plate, sump, thermostat, flywheel and you're pretty much there. Bit of a risk with an unknown engine from ebay, I'd put in a cheeky low bid and see what happens. Has the low oil pressure got worse?
 
Well I did just that and won it, it means I can drive till the old engine rattles then swop over gaining a higher compression head (stromburg carb for a tryout) distributor that matches etc. Will put new shell and oil pipm in.
Now I bet the old one goes on for ages now! Insurance!
 
Hello all
Thought I'd tack my oil pressure issue on the end of this one..... We have just come back from our first 'big' trip in Pootle and have done 1000 miles in last 3 weeks with no real issues. There are a few small things to tackle but biggest niggling worry is oil pressure. The engine has been rebuilt over lockdown and has now done about 1,500 miles. At cold the pressure is 40 psi at all speeds but once it is really upto normal temperatures (20 miles or so) then pressure drops to around 25psi when driving and perhaps 10 psi at idle (sometimes when hot at very slow idle the warning light comes on). I am using 20/50 oil and may try 20/60 for a test. I have looked at the pressure relief valve and apart from it looking a crap design I can't see any problem. When I rebuilt the engine I stupidly didn't replace the pump but a friend stripped and measured it and pronounced it within spec for clearances. I have read that the oil pipe in the timing case can give low pressure issues but doubt that would be temperature related? If I need to replace the oil pump, will the sump come off with the engine in the car or does the big chassis beam under the engine prevent removal? Must be a crappy dirty job but it would allow me to fit silicone gaskets I guess (another stupid error fitting old type seals....)
 
Oil pressure on a new engine should be 40/45psi so something isn't quite right. Did you re-grind the crank? The oil pump can be change from underneath, fiddly and mucky but it can be done. The steering arms need to be disconnected and it's a bit of a faff getting the sump off but do-able. While the sump is off take a look at the mains and make sure they haven't picked up (I think you've got to drop the crank anyway to get the pump out) and remember to position the dissy drive correctly before you pull the pump. Use assembly lube when putting it back together including the pump so it's easily primed, I prefer it to a squirt of oil.
 
10 psi isn't bad at tickover and shouldn't make to light come on, think it's about 7 psi for that to happen.

I'd still recommend starting simple with some easy bits first. The pressure relief valve just in case - 5 mins job and cheap. I think the new ones Martin has are updated (I think)? not sure would be the case with the scenario you describe though.

Also if the feed for the warning light and the oil pressure gauge is from the same engine point with a split connector probably worth checking that's not got crud in it - if the engines rebuilt there could be gunk floating around that may have blocked it slightly. Also check the wires are connected soundly (if the pressure gauge if electronic). Anyway of getting another gauge to double check the pressure before dropping the sump - as Panky says it can be done but is a bit of a pain.
 
Hi. I didn't grind the crank as journals looked good and measured within spec but did fit new shells - probably a false economy there.... I have a pressure gauge mounted on the engine and an electronic one fitted on the dash. Have checked both against a large one on my compressed air supply an all agree so readings should be good. I will check things by connecting another gauge to a second hole on the oil-way and also replace the bypass valve before delving into the pump and crank...
 
Hello again
OK back to review of Oil Pressure which still I feel is a bit low.
First step is to change the PRV but I can't get one to match the one I have which seems to be perhaps an unreliable variant
- it certainly doesn't look very good at sealing...
Pootle's filter block takes the brass valve on the right but the only valve I have been able to source is the one on the left which of course doesn't fit! I gave away the original Pootle engine when I rebuilt this Alpine engine so don't now have a second filter block to swap over..... BUM!

Well Martin didn't have one so I contacted Speedy's in Brighton and Sara was a gem with part numbers but didn't have one either. They did however have a used filter block for £35 which will take the steel valve and price doesn't seem bad after the big weekend shock....
- I called at local petrol station just to fill up a 1 gal can and the price? Holy cow, it's £8.75 - I had totally lost track of the 'real' cost with all this modern pounds/litre nonsense!
We shall see if new valve is a fix or I'm facing removing the sump and oil pump....
- Might also machine one of the new valves to be adjustable as many Alpine owners suggest....
Cheers
Tony
oil pressure relief valve.png
 
Last edited:
Pootle's Owner said:
Hello again
OK back to review of Oil Pressure which still I feel is a bit low.
First step is to change the PRV but I can't get one to match the one I have which seems to be perhaps an unreliable variant
- it certainly doesn't look very good at sealing...
Pootle's filter block takes the brass valve on the right but the only valve I have been able to source is the one on the left which of course doesn't fit! I gave away the original Pootle engine when I rebuilt this Alpine engine so don't now have a second filter block to swap over..... BUM!

Well Martin didn't have one so I contacted Speedy's in Brighton and Sara was a gem with part numbers but didn't have one either. They did however have a used filter block for £35 which will take the steel valve and price doesn't seem bad after the big weekend shock....
- I called at local petrol station just to fill up a 1 gal can and the price? Holy cow, it's £8.75 - I had totally lost track of the 'real' cost with all this modern pounds/litre nonsense!
We shall see if new valve is a fix or I'm facing removing the sump and oil pump....
- Might also machine one of the new valves to be adjustable as many Alpine owners suggest....
Cheers
Tony
View attachment 8271
Click to expand...
Well I received the used filter block from Speedy and it contains an old valve like the one on the left. So the I have fitted the new valve to the block and machined the old valve from Speedy to make it adjustable like this


At the weekend I'll fit the new block and experiment with valves to see what pressure I see in the oil system...
Cheers
Tony
 
Well I had trouble removing the old filter block as it was really stuck tight on the gasket but once the new one was fitted with the new PRV the oil pressure has improved significantly. At cold idle it's now at 60lbs/sqin. I need to take it for a run to get a real idea of what pressure is across the range but this does seem like a great result. At some point I'll experiment with the adjustable valve I have made but hopefully that will just be an academic exercise....
 
Did a short run today to get the engine temp to normal and did a long uphill drag to get the engine working. At cold the oil pressure was 60psi. After a good run the pressure was 40-45psi normally with 50psi when revving well. At slow idle pressure was 20psi and at a faster idle pressure was about 25-30psi. Looking at the Rootes book they claim 40-45 psi when warm with a 'new' engine so I think Pootle is pretty 'nominal' at this point and I can relax a little. Next step is rewire the mains circuit for the rear camper section and start restoring the paintwork...
 
Just to jump on the thread here..
I recently changed the oil and filter on my V8. I used the same oil as before ( I bought a 25l drum) and a different brand filter. I lost 15psi of oil pressure whether cold or hot. I went back to the original brand filter today. Got my 15psi back.
 
You must log in or register to reply here.
Back
Top